<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>uniqueRegExp</title>
</head>

<body>
    <div>打开浏览器控制台查看结果</div>
    <script>
        const uniqueRegExp = arr =>
            arr
                .sort()
                .join(',,')
                .replace(/(,|^)([^,]+)(,,\2)+(,|$)/g, '$1$2$4')
                .replace(/,,+/g, ',')
                .replace(/,$/, '')
                .split(',');
        console.log(uniqueRegExp([1, 2, 3, 1]));// [1,2,3]
    </script>
</body>

</html>